1. On the issues with Odd and Even Node Polarity
September 2016
doc.: IEEE /XXXXr0
November 2017
On the issues with Odd and Even Node Polarity
Date:
Name
Affiliation
Address
Phone
Rob Sun
Huawei
Yan Xin
Edward Au
Mengyao Ma
Rob Sun, Huawei
Intel Corporation

2. November 2017
Motivations
FB introduces the “Odd and Even Node Polarity” in [1] which defines the transmission pattern between DNs and CNs in the TDD sub-frames. The benefits are to improve the overall capacity and potentially reduce the interference.
However, we found this Odd and Even Node have the scalability and efficiency problem.
Sinking Hole Problem (SHP)
Uneven Traffic Problem (UTP)
Rob Sun, Huawei

3. Precursory Assumptions
November 2017
Precursory Assumptions
All the DNs and CNs are within the same BSS.
Each DN cannot receive multiple streams from different DNs simultaneously.
Realistically, Interference Cancellation is a hard problem.
Rob Sun, Huawei

4. September 2016
Intel Corporation

5. Problem Illustration (First TDD period)
November 2017
Problem Illustration (First TDD period) E
CN0
1) Link DN1DN2 could be interfered from DN3 (inter-DN interference)
2) Link DN3-DN2 could also be interfered from DN1 (inter-DN interference) E
CN1 O E O E
DN0
DN1
DN2
DN3 O
CN2
CN3
First TDD Sub-frame O
DN1DN0
DN1CN2
DN1CN3
Simultaneous
DN3DN2
CN0DN0
CN1DN0
DN1DN2
Rob Sun, Huawei

6. Problem Illustration (Second TDD period)
November 2017
Problem Illustration (Second TDD period) E
CN0
1) Link DN2 DN1 could be interfered by DN0 (inter-DN interference)
2) Link DN0DN1 could also be interfered by DN2 (inter-DN interference) E
CN1 O E O E
DN0
DN1
DN2
DN3 O
CN2
CN3 O O
Second TDD Sub-frame
DN0DN1
DN0CN0
DN0CN1
Simultaneous
DN2DN3
CN0DN1
CN1DN1
DN2DN1
Rob Sun, Huawei

7. The Sinking Hole Problem (SHP)
November 2017
The Sinking Hole Problem (SHP)
Due to the Odd and Even Node polarity settings and the inter-node interference, the Link between DN1 and DN2 can not be active during the both first and second time slots (SPs)
The SHP only applies to the backhaul links.
One possible solution to avoid the sinking hole problem is to dedicate the time slots (SPs) for the link between DN1 and DN2.
However, the latency will be noticeable.
and the scheduling will be complex.
To generalized this problem, the Odd and Even Node polarity scheme cannot scale up in large network.
Rob Sun, Huawei

8. Uneven Traffic Problem (UTP)
November 2017
Uneven Traffic Problem (UTP)
In this case, we are assuming DN0 is the end DN, DN1/DN2 are intermediate DNs, and DN3 is the portal to internet.
Also, we assume the Sinking Hole Problem could be solved.
We assume today’s traffic is uneven in both directions, i.e 80% of traffic are downlink and 20% of traffic are uplink.
We will observe the UTP due to the uneven traffic distribution.
Rob Sun, Huawei

9. Uneven Traffic Problem (UTP) Illustration
November 2017
Uneven Traffic Problem (UTP) Illustration E
CN0 E
CN1
DOWNLINK O E O
E (Portal)
DN0
DN1
DN2
DN3
Internet O
CN2
CN3
First TDD Sub-frame O
DN1DN0
DN1CN2
DN1CN3
Simultaneous
DN3DN2
CN0DN0
CN1DN0
DN1DN2
Unused
Rob Sun, Huawei

10. Uneven traffic problem (UTP) illustration
October, 2017
Uneven traffic problem (UTP) illustration E
CN0 E
CN1
UPLINK O E O
E(Portal)
DN0
DN1
DN2
DN3
Internet O
CN2
CN3 O O
Second TDD Sub-frame
DN0DN1
Unused
DN0CN0
DN0CN1
Simultaneous
DN2DN3
Unused
CN0DN1
CN1DN1
DN2DN1
Rob Sun, Huawei

11. Potential Solution To UTP
November 2017
Potential Solution To UTP
Change the rule of Odd and Even polarity setting for DNs links.
For instance, the Odd and Even polarity applies ONLY to DN-CN links.
The DN-DN links should not follow the Odd and Even polarity settings.
Enable each DN to send and receive simultaneously from different sources (new methods/technologies should be introduced).
Rob Sun, Huawei

12. Potential Solution Illustration (Downlink as Example)
November 2017
Potential Solution Illustration (Downlink as Example) E
CN0 E
CN1
DOWNLINK O E O
E (Portal)
DN0
DN1
DN2
DN3
Internet O
CN2
CN3
First TDD Sub-frame O
DN1DN0
DN1CN2
DN1CN3
Simultaneous
DN3DN2
CN0DN0
CN1DN0
DN2DN1
Rob Sun, Huawei

13. November 2017
References
[1] IEEE /1321r1 “Features for mmW Distribution Network Use Case”
Rob Sun, Huawei